Skin Disease Flashcards
Sheep scab
- facts (3)
- epidemiology (4)
- psoroptes ovis
- highly contagious
- welfare and economical problem
- mites can live in environment fo rup to 17 days
- direct contact: mite to wool (spread on trucks etc. as well)
- winter/spring
- will reside in ears in summer/autumn
Sheep Scab
- pathogenesis (4)
- CS (3)
- Dx (2)
- Tx
- control (3)
- 3-21 days before onset of CS
- immediate and delayed hypersensitivity type IV reaction
- inflammation: microclimate favourable for mite
- serous exudate: nutrition for mite.
CS:
- discolouration of wool by serous exudate (initially shoulders/loin)
- intense pruritus: nibbling reflex
- wool los
Dx:
- skin scrape from edge of lesion
- ELISA antibody test
Tx: organophosphate dip or systemic endectocide injection (ML)
Control:
- coordinate Tx with neighbour
- treat all sheep at same time
- treat environment
Sheep scab order 2010 Scotland
- Movement restrictions
- can move for treatment, slaughter or under licence
- treat al sheep in flock and notify APHA
- Describes an infestation
- notification on suspicion
- allows vet inspector to take samples
Blowfly Strike (myiasis)
- facts (3)
- pathoenesis
- summer months (may-sept)
- attracted to soiled areas (breech, skin lesions, footrot)
- ewes prior to shearing
larvae penetrate skin and secrete enzymes –> irritation –> secondary bacterial infection –> toxaemia
Blowfly Strike (myiasis)
- CS (5)
- control (6)
CS:
- restlessness, bite/kick affected area
- discoloured, moist wol and offensive smell
- wool loss and moist dermatitis
- toxaemia
- death
control:
- change to wool-shedding breed
- shear sheep
- plunge dipping(OG
- pour ons
- synthetic pyrethroids (up to 10 weeks, kills larvae)
- IGR (up to 16 weeks, prevent larvae developing)
Lice types and names
chewing: bovicola ovia
sucking:
- linognathus ovillus (face
- linognathus pedalis (limbs)
Chewing lice
- Facts (4)
- CS (4)
- Dx
- Tx (3)
- entire life spent on host
- complete lifecycle is 30 days, adults live for 30 days
- autumn/winter
- requires close contact: slow spread
CS:
- dorsum and flank
- irritation and intense pruritis
- rubbing/biting shoulders, flanks and back
- broken wool, matting and discolouration
Dx: visable to naked eye
Tx:
- shearing
- OP dipping
- synthetic pour-ons
Ticks
- type
- transmissible diseases
ixodes ricinus
- tick-borne fever
- looping ill
- tick pyaemia
- Q fever
- baesiosis
OP
Advantages (4)
disadvantages (5)
how to use
+ve
- kills mites within 24 hours
- washing effect removes dead mites
- residual effect for several weeks
- also controls blowfly, lice, keds and ticks
- ve
- human and environmental hazard
- operator needs certificate
- adequate facilities?
- stressful procedure for sheep
- long meat withdrawal (70 days)
- sheep must be immersed for at least 1 minute whit head submerged twice
- sheep should be clean and dry (bring in the night before)
- concentration of acive agentdecreases with sheep dippings: top up
ML
advantages (3)
disadvantages (5)
types (3)
+ve
- less complex to administer
- safer for operator, sheep and environment
- residual protection for several weeks
- ve:
- pruritis may persist for up to 30 days
- takes time to kill mites
- promotes anthelmintic resistance
- narrow range of efficacy against other ectoparasites
- may not treat all animals with correct dose
-moxidectin, doramectin, ivermectin
Orf
- Facts (5)
- CS (2)
- parapox virus
- zoonotic: use gloves with vaccine and animal
- no colostral immunity
- seen in 4-5 month old lambs
- scabs contain live virus
CS:
- proliferative lesions on lips and nostrils
- lesions on teats
Orf
epidemiology (4)
Dx (2)
Tx (2)
- dry scab is infection for several months
- persistently infected carriers
- low mortality but poorly growing lambs
- hungry, infected lambs steal milk form other mothers so spreads quickly
Dx:
- CS
- virus culture
notifiable DDX: foot and mouth, bluetongue, sheep pox
Tx:
- natural recovery in 24-30 days
- nursing
Caseous lymphadenitis
- Facts (4)
- CS (2)
- Dx (2)
- Tx
- corynebacterum psudeotuberculosis
- via skin abrasion
- abscesses in regional LNs
- survive up to 5 months in soils/shed
CS:
-Frim, palpable swellings involving LNs of head and neck (25% only internally and show only ill thrift)
Dx:
- bacteriological culture (not always on first go)
- serology -ELISA
Tx: Cull
Photosensitisation
- Types (2)
- CS (2)
- Tx
- primary: eat plants containing photodynamic agents (st johns wart)
- secondary: accumulation of chlorophyll metabolites
CS: skin necrotic and sloughing (mainly unpigmented skin), may also affect wool parting
Tx: keep housed until lesions heal
Dermatophilosis (lumpy wool) (5)
- Dermatophilosis congolensis
- associated with wet weather
- papule and crust formation on ears, nose and dorsum
- NOT pruritic
- self limiting/penicillin
